Baiku

Having a バイク　(Baiku/Motorcycle) is awesome.  You get better gas mileage, get the wind in your face, you look cool, and get crazy chicks.  Unfortunately, Japan makes the process of owning a bike, as with owning a car, overly complicated and costly - which is probably what "CCs" stands for.

Lets start with the good stuff.  Japan still has Harleys.  I've noticed they are pretty popular and the shops are in every major city.  I've only been able to afford their t-shirts but someday a Harley may be in my future.

Japan also has WAY cooler bikes than the US.  Japan, much like Europe, requires separate licenses for small (less than 125cc), medium (125 to 400), and large (greater than 400) bikes.  As a result they have a bunch of cool designs that dance right on the lines between licenses.  Just go ahead and compare the bikes between the Honda US website and the Honda Japan website, or Kawasaki, Yamaha, Suzuki, etc.  Japan has at least twice as many designs, and most of then are less than 400ccs.  A 125cc sport bike is unheard of in the states because everyone in america 'outgrows' 250cc bikes in a couple months, but that is the perfect bike for Japan or really anyone new to riding.  Japan is full of mountains and twisties.  Who needs to go 180mph when you can cruise the mountains of japan on a 125cc bike that cost you less than 4 grand?

One down side that comes with all that variety is my American motorcycle license doesn't completely transfer to Japan.  An American motorcycle endorsement only allows me to ride up to medium sized bikes.  Unfortunately to ride a "Large" bike you need a separate test, fee, those little passport photos you get from booths by the train station, etc.

You may have already noticed that bikes in Japan are more expensive.  My american bought CB500F is a CB400F in Japan, but Japan charges a grand more for it.  This is pretty universal with the exception of some of the big bikes.  Due to the issue above with the extra hassle of getting a large bike license, some of the larger bikes go for a little less in Japan compared to stateside.  Particularly if the yen gets weak again, you can save a pretty penny buying a big bike in Japan.  Not Harleys though, those bikes are expensive no matter where you buy them.

If you're not quite ready for a Baiku, try out a scooter.  They're freakin everywhere in Japan!  I'm pretty sure getting the license only involves a written test, which people talk about here.

Whatever you decide, there are plenty of places in Japan that you can't get to via public transportation, so I strongly recommend having a personal vehicle to hit up beaches and popular hiking/nature trails in Japan that are secluded from the waves of people you come to expect.  Find your own part of Japan and enjoy it.  Might I recommend Yamanashi?